# Use --installed to limit to installed packages only
function __fish_print_packages
    argparse --name=__fish_print_packages i/installed -- $argv
    or return

    set -l only_installed 1
    if not set -q _flag_installed
        set -e only_installed
    end

    # apt-cache is much, much faster than rpm, and can do this in real
    # time. We use it if available.

    switch (commandline -ct)
        case '-**'
            return
    end

    if type -q -f apt-cache
        if not set -q only_installed
            # Do not generate the cache as apparently sometimes this is slow.
            # http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=547550
            # (It is safe to use `sed -r` here as we are guaranteed to be on a GNU platform
            # if apt-cache was found. Using unicode reserved range in `fish/tr` and the
            # little-endian bytecode equivalent in `sed`. Supports localization.)
            apt-cache --no-generate show '.*'(commandline -ct)'.*' 2>/dev/null | sed -r '/^(Package|Description-?[a-z]{0,2}):/!d;s/Package: (.*)/\1\t/g;s/Description-?[^:]*: (.*)/\1\xee\x80\x80\x0a/g' | tr -d \n | tr -s \uE000 \n | uniq
            return
        else
            set -l packages (dpkg --get-selections | string replace -fr '(\S+)\s+install' "\$1" | string match -e (commandline -ct))
            apt-cache --no-generate show $packages 2>/dev/null | sed -r '/^(Package|Description-?[a-z]{0,2}):/!d;s/Package: (.*)/\1\t/g;s/Description-?[^:]*: (.*)/\1\xee\x80\x80\x0a/g' | tr -d \n | tr -s \uE000 \n | uniq

            return
        end
    end

    # Pkg is fast on FreeBSD and provides versioning info which we want for
    # installed packages
    if type -q -f pkg
        pkg query "%n-%v"
        return
    end

    # pkg_info on OpenBSD provides versioning info which we want for
    # installed packages but, calling it directly can cause delays in
    # returning information if another pkg_* tool have a lock.
    # Listing /var/db/pkg is a clean alternative.
    if type -q -f pkg_add
        set -l files /var/db/pkg/*
        string replace /var/db/pkg/ '' -- $files
        return
    end

    ### BEGIN CACHED RESULTS ###

    # Set up cache directory
    set -l xdg_cache_home $XDG_CACHE_HOME
    if test -z "$xdg_cache_home"
        set xdg_cache_home $HOME/.cache
    end
    mkdir -m 700 -p $xdg_cache_home

    # Caches for 5 minutes
    if type -q -f pacman
        if not set -q only_installed
            set -l cache_file $xdg_cache_home/.pac-cache.$USER
            if test -f $cache_file
                cat $cache_file
                set -l age (math (date +%s) - (stat -c '%Y' $cache_file))
                set -l max_age 250
                if test $age -lt $max_age
                    return
                end
            end
            # prints: <package name>	Package
            pacman -Ssq | sed -e 's/$/\t'Package'/' >$cache_file &
            return
        else
            pacman -Q | string replace ' ' \t
            return
        end
    end

    # Zypper needs caching as it is slow
    if type -q -f zypper
        # Use libzypp cache file if available
        if test -f /var/cache/zypp/solv/@System/solv.idx
            awk '!/application:|srcpackage:|product:|pattern:|patch:/ {print $1'\tPackage'}' /var/cache/zypp/solv/*/solv.idx
            return
        end

        # If the cache is less than five minutes old, we do not recalculate it

        set -l cache_file $xdg_cache_home/.zypper-cache.$USER
        if test -f $cache_file
            cat $cache_file
            set -l age (math (date +%s) - (stat -c '%Y' $cache_file))
            set -l max_age 300
            if test $age -lt $max_age
                return
            end
        end

        # Remove package version information from output and pipe into cache file
        zypper --quiet --non-interactive search --type=package | tail -n +4 | sed -r 's/^. \| ((\w|[-_.])+).*/\1\t'Package'/g' >$cache_file &
        return
    end

    # yum is slow, just like rpm, so go to the background
    if type -q -f /usr/share/yum-cli/completion-helper.py

        # If the cache is less than six hours old, we do not recalculate it

        set -l cache_file $xdg_cache_home/.yum-cache.$USER
        if test -f $cache_file
            cat $cache_file
            set -l age (math (date +%s) - (stat -c '%Y' $cache_file))
            set -l max_age 21600
            if test $age -lt $max_age
                return
            end
        end

        # Remove package version information from output and pipe into cache file
        /usr/share/yum-cli/completion-helper.py list all -d 0 -C | sed "s/\..*/\tPackage/" >$cache_file &
        return
    end

    # Rpm is too slow for this job, so we set it up to do completions
    # as a background job and cache the results.

    if type -q -f rpm

        # If the cache is less than five minutes old, we do not recalculate it

        set -l cache_file $xdg_cache_home/.rpm-cache.$USER
        if test -f $cache_file
            cat $cache_file
            set -l age (math (date +%s) - (stat -c '%Y' $cache_file))
            set -l max_age 250
            if test $age -lt $max_age
                return
            end
        end

        # Remove package version information from output and pipe into cache file
        rpm -qa | sed -e 's/-[^-]*-[^-]*$/\t'Package'/' >$cache_file &
        return
    end

    # Eopkg is slow in showing list of available packages

    if type -q -f eopkg

        # If the cache is less than max_age, we do not recalculate it
        # Determine whether to print installed/available packages

        if set -q only_installed
            set -l cache_file $xdg_cache_home/.eopkg-installed-cache.$USER
            if test -f $cache_file
                cat $cache_file
                set -l age (math (date +%s) - (stat -c '%Y' $cache_file))
                set -l max_age 500
                if test $age -lt $max_age
                    return
                end
            end

            # Remove package version information from output and pipe into cache file
            eopkg list-installed -N | cut -d ' ' -f 1 >$cache_file &
            return
        else
            set -l cache_file $xdg_cache_home/.eopkg-available-cache.$USER
            if test -f $cache_file
                cat $cache_file
                set -l age (math (date +%s) - (stat -c '%Y' $cache_file))
                set -l max_age 500
                if test $age -lt $max_age
                    return
                end
            end

            # Remove package version information from output and pipe into cache file
            eopkg list-available -N | cut -d ' ' -f 1 >$cache_file &
            return
        end
    end

    # This completes the package name from the portage tree.
    # True for installing new packages. Function for printing
    # installed on the system packages is in completions/emerge.fish

    # eix is MUCH faster than emerge so use it if it is available
    if type -q -f eix
        eix --only-names "^"(commandline -ct) | cut -d/ -f2
        return
    else
        # FIXME?  Seems to be broken
        if type -q -f emerge
            emerge -s \^(commandline -ct) | string match -r "^\*.*" | cut -d' ' -f3 | cut -d/ -f2
            return
        end
    end

    # port needs caching, as it tends to be slow
    # BSD find is used for determining file age because HFS+ and APFS
    # don't save unix time, but the actual date. Also BSD stat is vastly
    # different from linux stat and converting its time format is tedious
    if type -q -f port
        set -l cache_file $xdg_cache_home/.port-cache.$USER
        if test -e $cache_file
            # Delete if cache is older than 15 minutes
            find "$cache_file" -ctime +15m | awk '{$1=$1;print}' | xargs rm
            if test -f $cache_file
                cat $cache_file
                return
            end
        end
        # Remove trailing whitespace and pipe into cache file
        printf "all\ncurrent\nactive\ninactive\ninstalled\nuninstalled\noutdated" >$cache_file
        port echo all | awk '{$1=$1};1' >>$cache_file &
        cat $cache_file
        return
    end

    if type -q -f opkg
        if set -q only_installed
            opkg list-installed 2>/dev/null | sed -r 's/^([a-zA-Z0-9\-]+) - ([a-zA-Z0-9\-]+)/\1\t\2/g'
            return
        else
            opkg list 2>/dev/null | sed -r 's/^([a-zA-Z0-9\-]+) - ([a-zA-Z0-9\-]+)/\1\t\2/g'
            return
        end
    end

    if type -q -f apk
        if set -q only_installed
            apk info -q
            return
        else
            apk search -q
            return
        end
    end

    # Caches for 5 minutes
    if type -q -f xbps-query
        if not set -q only_installed
            set -l cache_file $xdg_cache_home/.xbps-cache.$USER
            if test -f $cache_file
                cat $cache_file
                set -l age (math (date +%s) - (stat -c '%Y' $cache_file))
                set -l max_age 300
                if test $age -lt $max_age
                    return
                end
            end
            # prints: <package name>	Package
            xbps-query -Rsl | sed 's/^... \([^ ]*\)-.* .*/\1/; s/$/\t'Package'/' >$cache_file &
            return
        else
            xbps-query -l | sed 's/^.. \([^ ]*\)-.* .*/\1/' # TODO: actually put package versions in tab for locally installed packages
            return
        end
    end

end